Optical disk cartridge

ABSTRACT

An optical disk cartridge includes a casing having a pair of walls for accommodating an optical disk therein. In the optical disk cartridge, the walls of the casing are formed with clamping windows for clamping the disk at the central portions thereof, and are formed with reading and writing windows for reading information from the disk and writing information on the disk from the clamping windows to side edges of the casing. A shutter capable of opening and closing the clamping windows and the reading and writing windows is slidably provided. The horizontal size of the clamping windows along a sliding direction of the shutter is formed shorter than the vertical size thereof orthogonal to the sliding direction of the shutter.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an optical disk cartridge for DVD-RAMs (digital versatile disk RAMs), and more particularly, relates to an optical disk cartridge suitable for use with 80 mm disks.

2. Description of the Related Art

Some optical disks, such as some CDs and DVDS, used while being accommodated in an optical disk cartridge.

A conventional disk cartridge for accommodating therein large (120 mm) disks will be described with reference to FIGS. 30 and 31.

Top and bottom faces of a casing 21 are formed with clamping windows 21 a opposing the center of the casing 21, and are formed with reading and writing windows 21 b connected to the clamping windows 21 a.

Each of the clamping windows 21 a consists of a semicircular portion (R1 is about 17 mm) and a portion connected from the circular portion to each of the reading and writing windows 21 a.

When an optical disk cartridge is loaded on a disk driving apparatus 22, as shown in FIG. 31, a shutter is moved to open the clamping windows 21 a and the reading and writing windows 21 b.

When the disk D is loaded, a table 23 enters into the clamping window 21 a formed in the bottom face of the casing 21, and a clamper (not shown) enters into the clamping window 21 a formed in the top face of the casing 21, whereby the disk D in the casing 21 is clamped while being slightly raised.

An optical head 24 is moved along the reading and writing windows 21 b, whereby information is read from the disk D and is written on the disk D.

In order to smoothly insert the table 23 and the clamper into the clamping windows 21 a, it is necessary to form opening areas of the clamping windows 21 a larger than the table 23 or the clamper with clearance therebetween.

In particular, in an optical disk cartridge in which the table 23 is rotated about a fulcrum 25 to enter the clamping windows 21 a, as shown in FIG. 31, a terminal edge 26 of the table 23 easily interferes with the peripheries of the clamping windows 21 a, and it is necessary to form the clamping windows 21 a larger than the table 23 with sufficient clearance.

According to an optical disk cartridge for accommodating therein small (80 mm) disks, it is difficult to form large (equivalent to 120 mm) clamping windows 21 a. If the clamping windows 21 a are enlarged, the width of the shutter for closing the clamping windows 21 a is correspondingly increased, and side edges of the shutter may be extruded from the casing 1 when the shutter is slid to an opening position.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide an optical disk cartridge which can form a large clamping window while preventing a shutter at an opening position from being extruded from a casing.

In accordance with the present invention, there is provided an optical disk cartridge including a casing having a pair of walls for accommodating an optical disk therein; wherein the walls of the casing are formed with clamping windows for clamping the disk at the central portions thereof, and are formed with reading and writing windows for reading information from the disk and writing information on the disk from the clamping windows to side edges of the casing; a shutter capable of opening and closing the clamping windows and the reading and writing windows is slidably provided, and the horizontal size of the clamping windows along a sliding direction of the shutter is formed shorter than the vertical size thereof orthogonal to the sliding direction of the shutter.

In the optical disk cartridge of the present invention, the clamping windows may be formed by linear parts opposing along the sliding direction of the shutter, and arcuate parts connecting the linear parts, and a distance between the linear parts may be shorter than a diameter of the arcuate parts.

In addition, the diameter of the arcuate parts of the clamping windows may be ±2 mm of 28 mm, and the distance between the linear parts may be ±2 mm of 27.4 mm.

In the optical disk cartridge of the present invention, projections for narrowing the width of the reading and writing windows may be formed on the border of the clamping windows and the reading and clamping windows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an optical disk cartridge according to the present invention;

FIG. 2 is a perspective view of the optical disk cartridge shown in FIG. 1 that has been turned upside down;

FIG. 3 is a front view of the optical cartridge according to the present invention;

FIG. 4 is a sectional view taken along the line 4—4 in FIG. 1;

FIG. 5 is a sectional view taken along the line 5—5 in FIG. 3;

FIG. 6 is an enlarged view of a portion identified by Z in FIG. 5;

FIG. 7 is a sectional view taken along the line 7—7 in FIG. 6;

FIG. 8 illustrates movement of an operation part and an operation element of the optical disc cartridge;

FIG. 9 is a sectional view taken along the line 9—9 in FIG. 8;

FIG. 10 illustrates the relationship between the optical disk cartridge and a disk driving apparatus according to the present invention;

FIG. 11 is a plan view of a bottom cover in the optical disk cartridge according to the present invention;

FIG. 12 is a side view of the bottom cover;

FIG. 13 is a front view of the bottom cover;

FIG. 14 is a rear elevation view of the bottom cover;

FIG. 15 is an enlarged sectional view of a portion identified by X in FIG. 11;

FIG. 16 is a plan view of a holder for the optical disk cartridge;

FIG. 17 is a front view of the holder;

FIG. 18 is a side view of the holder;

FIG. 19 is a rear elevation view of the holder;

FIG. 20 is a partial view showing a principal part of the holder;

FIG. 21 is a sectional view taken along the line 21—21 in FIG. 20;

FIG. 22 is a sectional view taken along the line 22—22 in FIG. 20;

FIG. 23 is a partial view showing a principal part of the holder;

FIG. 24 is a sectional view taken along the line 24—24 in FIG. 23;

FIG. 25 is a sectional view taken along the line 25—25 in FIG. 23;

FIG. 26 is a plan view of the operation part of the optical disk cartridge;

FIG. 27 is a sectional view taken along the line 27—27 in FIG. 26;

FIG. 28 is a plan view of the operation element of the optical disk cartridge;

FIG. 29 is a sectional view taken along the line 29—29 in FIG. 28;

FIG. 30 is a plan view of a conventional optical disk cartridge; and

FIG. 31 illustrates the relationship between the conventional optical disk cartridge and a disk driving apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENT

While optical disk cartridges exist for DVD-RAM disks of 120 mm in diameter, optical disk cartridges for DVD-RAM disks of 80 mm in diameter have not previously been developed.

The present invention provides an optical disk cartridge for 80 mm disks which can also be applied to optical disk cartridges for 120 mm disks, and to a disk driving apparatus for the optical disk cartridge for 120 mm disks.

An embodiment of an optical disk cartridge of the present invention applied to the 80-mm disks used for a DVD-RAM will now be described with reference to FIGS. 1 to 29.

A casing 1 consists of top and bottom covers 2 and 3 which are molded articles made of synthetic resin.

Since the top and bottom covers 2 and 3 have nearly the same construction, only the bottom cover 3 will be described in detail. Regarding the top cover 2, portions thereof which differ from those of the bottom cover 3 will also be described.

As shown in FIGS. 1 to 15, the bottom cover 3 includes a planar wall 3 a, a pair of side walls 3 b provided on the left and right of the wall 3 a, and a rectangular cutout 3 e which is formed in front of the wall 3 a with spaces 3 c and 3 d remaining between the side walls 3 b.

In addition, the bottom cover 3 includes front walls 3 f and 3 g provided at left and right front positions corresponding to the spaces 3 c and 3 d. The front walls 3 f and 3 g are provided with recesses 3 h of different shapes at positions exposed to the outside so as to form incorrect-insertion-preventing sections A.

As shown in FIGS. 11 to 15, the space 3 c of the wall 3 a is provided with operating slots 3 i and 3 j, and a breakable blocking part 3 m consisting of a projection and having thin-walled parts 3 k at the base portion thereof which are sequentially arranged side by side.

The space 3 d of the wall 3 a is provided with a circular discrimination hole 3 n for discriminating whether or not information can be written on the disk, a circular discrimination hole 3 p for discriminating whether or not the checking for defective regions has been completed, and a circular blocking part-removing hole 3 q, all of which are sequentially arranged side by side. The discrimination hole 3 n and the operating slot 3 i, the discrimination hole 3 p and the operating slot 3 j, and the hole 3 q and the blocking part 3 m are provided at positions equidistant from the center of the wall 3 a.

The bottom cover 3 includes a spring receiver 3 r formed on the rear thereof, a substantially circular clamping window 3 s formed in the center thereof, a rectangular reading and writing window 3 t provided continuously with the clamping window 3 s. Projections 3 u are formed on the border of the clamping window 3 s and the reading and writing windows 3 t so as to narrow the width of the window 3 t. An arcuate rim 3 v is provided on the rear of the inside of the bottom cover 3. Regulating parts 3 w are connected to both ends of the rim 3 v and extending rearward inclined relative to the side walls 3 b. A base 3 x is provided over the central portion of the inside of the bottom cover 3, a pair of latching recesses 3 y are provided at opposing positions of the side walls 3 b, and a rectangular recessed part 3 z is provided on the back of the wall 3 a of the bottom cover 3.

Referring to FIG. 11, in the window 3 t for reading and writing, an optical head (not shown) linearly moves so as to read and write information from and onto the disk D. When the direction of movement of the optical head is taken as a vertical direction E, and the direction orthogonal to the vertical direction E is taken as a horizontal direction F, the clamping window 3 s is formed by arcuate parts J each having a radius of 14 mm from the center C of the window 3 s (the same as the center C of the disk D. In other words, clamping window 3 s has diameter G of 28 mm in the vertical direction E, and linear parts K having a distance therebetween of 27.4 mm parallel to the direction of movement of the optical head, (i.e., the vertical direction E). The arcuate parts J connect the linear parts K.

That is, the clamping window 3 s has the horizontal size H along a sliding direction of a shutter which is formed shorter than the vertical size G orthogonal to the sliding direction of the shutter, and has a diameter G (28 mm) in the vertical direction E which is formed larger than the distance H (27.4 mm) in the horizontal direction F.

The same construction applies to a clamping window 2 s of the top cover 2, and the diameter G may preferably be ±2 mm of 28 mm, and the width H may preferably be ±2 mm due to the relationship between the entire width of the casing 1 for the 80 mm disk and a motor and shutter (described hereinbelow) of the disk driving apparatus for the 120 mm disk.

The details of the top cover 2 are omitted, and only some of the components and the reference numerals thereof are shown in the figures.

As will be understood from a comparison of FIG. 1 and FIG. 2, the top cover 2 differs from the bottom cover 3 in that a recessed part 2 z is formed on the surface of the wall 2 a of the top cover 2, in that a space 2 f of the wall 2 a is provided with a discrimination hole 2 n for discriminating whether or not the information can be written on the disk D, a discrimination hole 2 p for determining whether or not the checking for defective regions has been completed, and a blocking part-removing hole 2 q. The top cover 2 also differs in that a space 2 g of the wall 2 a is provided with operating slots 2 i and 2 j arranged side by side, and a breakable blocking part 2 m consisting of a projection and having thin-walled parts 2 k at the base portion thereof.

The top cover 2 and the bottom cover 3 constructed as described above are combined vertically to thereby form the casing 1.

When the top and bottom covers 2 and 3 are combined, an accommodating section 1 a for accommodating the optical disk D and the like is formed therebetween, and the incorrect-insertion-preventing sections A having recesses of different shapes are formed between the front walls 2 f, 2 g, 3 f and 3 g, as shown in FIG. 3.

In addition, when the top and bottom covers 2 and 3 are combined, the discrimination hole 2 n of the top cover opposes a part of the operating slot 3 i of the bottom cover 3, the discrimination hole 2 p opposes a part of the operating slot 3 j, the hole 2 q opposes the blocking part 3 m on the right side of the casing 1, the discrimination hole 3 n of the bottom cover 3 opposes a part of the operating slot 2 i of the top cover 2, the discrimination hole 3 p opposes a part of the operating slot 2 j, and the blocking part 2 m opposes the hole 3 q on the left side of the casing 1.

Closing parts 1 b for closing the operating slots 3 i and 3 j are formed adjacent to the discrimination holes 2 n and 2 p of the wall 2 a opposing the operating slots 3 i and 3 j, and closing parts 1 c for closing the operating slots 2 i and 2 j are formed adjacent to the discrimination holes 3 n and 3 p of the wall 3 a opposing the operating slots 2 i and 2 j.

Furthermore, when the top and bottom covers 2 and 3 are combined, a clamping window 2 s and a reading and writing window 2 t of the top cover 2 opposes the clamping window 3 s and the reading and writing window 3 t of the bottom cover 3. A rim 2 v and regulating parts 2 w of the top cover 2 abut against the rim 3 v and the regulating parts 3 w of the bottom cover 3, a space for holding the disk D is secured between bases 2 x and 3 x, and latching recesses 2 y and 3 y are formed in the side walls 2 b and 3 b.

A shutter 4 is made of a U-shaped metal plate and consists of a rectangular plate part 4 a for closing the clamping window 2 s and the reading and writing window 2 t, a rectangular plate part 4 b for closing the clamping window 3 s and the reading and writing window 3 t, and a connecting part 4 c for connecting the plate parts 4 a and 4 b.

The connecting part 4 c is located on the rear of the casing 1. The plate parts 4 a and 4 b are disposed in the recessed parts 2 z and 3 z so that the shutter 4 can move within the range of the recessed parts 2 z and 3 z.

Spring members (not shown) are placed in the spring receivers 2 r and 3 r, and the shutter 4 is normally located by the spring members at a neutral position to close the clamping windows 2 s and 3 s and the reading and writing windows 2 t and 3 t. When the shutter 4 is moved to the right side or the left side against the spring members, the shutter 4 opens the windows 2 s, 3 s, 2 t, and 3 t. When the biasing force to the shutter 4 is terminated, the shutter 4 is returned by the spring members to the neutral position again to close the windows 2 s, 3 s, 2 t, and 3 t.

As shown in FIGS. 16 to 19, a holder 5, which is a molded article made of synthetic resin includes a base part 5 a, a pair of elastic arms 5 b provided at both ends of the base part 5 a and extending rearward, a pair of triangular projections 5 c provided at the terminal ends of the elastic arms 5 b, holding parts 5 d projecting from the upper and lower surfaces of the elastic arms 5 b near the terminal ends of the elastic arms 5 b, an exposed part 5 e continuously connected to the inner surfaces of the elastic arms 5 b to form the base part 5 a, and a groove 5 f provided behind the exposed part 5 e.

The elastic arms 5 b have spring properties on the side of the disk D (i.e., biasing inwardly toward each other). The disk D is inserted into the groove 5 f between the elastic arms 5 b. The holding parts 5 d hold a part of the upper and lower surfaces of the disk D, and the elastic arms 5 b hold the left and right peripheries of the disk D.

In addition, as shown in FIG. 16, the elastic arms 5 b extend rearward from the base part 5 a while exceeding the size of the radius R of the disk D, and the holding parts 5 d are formed at positions beyond the radius R of the disk D so as to hold the disk D at positions rearward of the center C of the disk D from the base part 5 a.

The holder 5 can be inserted into and removed from the accommodating section 1 a with the disk D held by the elastic arms 5 b. When the holder 5 is accommodated in the accommodating section 1 a together with the disk D, the projections 5 c abut against the regulating parts 2 w and 3 w, as shown in FIG. 5. When the holder 5 is further pushed in, the elastic arms 5 b are spread outwardly to separate from the peripheries of the disk D, whereby the holding of the peripheries of the disk D by the elastic arms 5 b is released. The deformation of the elastic arms 5 c toward the disk D is prevented by the regulating parts 2 w and 3 w.

When the holder 5 is mounted in the casing 1, the exposed part 5 e is located in the cutouts 2 e and 3 e so as to be exposed.

In removing the holder 5 from the casing 1, the elastic arms 5 b separate from the regulating parts 2 w and 3 w and return toward the disk D due to the spring properties thereof to hold the disk D, whereby the holder 5 can be removed together with the disk D held thereby.

The holder 5 includes a pair of extended parts 5 g located on both sides of the exposed part 5 e to form a part of the base part 5 a. A pair of first receiving parts 5 h, each comprising a substantially rectangular hole are provided in the pair of extended parts 5 g at positions equidistant from the widthwise central part of the holder 5. First guide parts 5 i, each consisting of side walls forming the receiving parts 5 h, and a pair of V-shaped recesses 5 j spaced apart in the first guide parts 5 i.

The first receiving parts 5 h coincide with the discrimination holes 2 n and 3 n provided in the top and bottom covers 2 and 3, respectively.

The holder 5 also includes a pair of second receiving parts 5 k, each comprising a substantially rectangular wide hole, provided in the outside of the first receiving parts 5 h at positions equidistant from the widthwise central part of the holder 5, second guide parts 5 m each consisting of side walls forming the receiving parts 5 k, and a pair of V-shaped recesses 5 n spaced apart in the second guide parts 5 m.

The second receiving parts 5 k coincide with the discrimination holes 2 p and 3 p provided in the top and bottom covers 2 and 3, respectively, and blocking parts 2 m and 3 m.

In addition, the holder 5 includes identification marks 5 p formed on top and bottom faces of the exposed part 5 e. Each of the identification marks 5 p consists of an elliptical recess 5 q and a projection 5 r provided on the recess 5 q. As shown in FIGS. 20 to 25, one projection 5 r is provided on the top face of the base part 5 a, and two projections 5 r are provided on the bottom face of the base part 5 a so that top and bottom faces of each of the identification marks 5 p can be identified tactilly.

The holder 5 includes incorrect-insertion-preventing sections B provided on the extended parts 5 g. The incorrect-insertion-preventing sections B have recesses 5 s of different shapes provided in the left and right extended parts 5 g, as shown in FIG. 17. The incorrect-insertion-preventing sections B of the holder 5 coincide with the incorrect-insertion-preventing sections A formed on the casing 1. If the holder 5 is turned upside down and an attempt is made to insert it into the casing 1, the incorrect-insertion-preventing sections A and B prevent the holder 5 from being inserted into the casing 1.

The holder 5 includes a pair of locking parts 5 t, each having spring properties, provided on both sides thereof. When the holder 5 is inserted into the accommodating section 1 a of the casing 1, the latching parts 5 t are inserted into the casing 1 in a state of elastically contacting the side walls 2 b and 3 b of the top and bottom covers 2 and 3. When the latching parts 5 t coincide with the latching recesses 2 y and 3 y, the latching parts 5 t spread out due to the spring properties thereof to be latched in the latching recesses 2 y and 3 y, whereby the holder 5 is mounted in the casing 1.

In removing the holder 5 from the casing 1, the latching parts 5 t are first pressed toward the inside of the casing 1 from the outside of the casing 1 to unlatch the latching parts 5 t from the latching recesses 2 y and 3 y, and then the base part 5 a of the holder is pulled out.

An operation is a molded article made of synthetic resin, includes a rectangular sealing part 6 a, a recess 6 b formed in the sealing part 6 a, and an engaging part 6 c having spring properties which extends from one end of the sealing part 6 a, as shown in FIGS. 26 and 27.

The operation part 6 is accommodated by the holder 5 in the accommodating section 1 a of the casing 1 in a state of being received in the first receiving part 5 h so that the recess 6 b opposes the operating slot 2 i of the top cover 2, as shown in FIGS. 5 to 9.

When the operation part 6 is accommodated, the upper and lower surfaces of the operation part 6 are clamped by the top and bottom covers 2 and 3, side surfaces abut against the first guide 5 i, and the engaging part 6 c is engaged with the recess 5 j.

That is, the operation part 6 is slidably mounted without entering into the operating slot 2 i of the top cover 2 and the discrimination hole 3 n of the bottom cover 3.

As shown in FIGS. 6 and 7, when the operation part 6 is at a position near the front of the casing 1, the discrimination hole 3 n is closed by the sealing part 6 a of the operation part 6 to prevent a detection pin (not shown), provided on the disk driving apparatus, from entering the discrimination hole 3 n, whereby the information can be written on the disk D. When an operating tool (not shown) is passed through the operating hole 2 i to be engaged with the recess 6 b of the operation part 6, and the operation part 6 is slid along the operating slot 2 i in the direction to separate from the front of the casing 1, the operation part 6 slides using the first guide part 5 i as a guide and the engaging part 6 c engages with another recess 5 j, whereby the operation part 6 is positioned, as shown in FIGS. 8 and 9.

In this case, the sealing part 6 a of the operation part 6 opens the discrimination hole 3 n and enables the entry of the detection pin so as to protect the disk D from having information written thereon.

In this way, the sliding movement of the operation part 6 determines whether or not information can be written on the disk D.

The operation part 6 disposed on the left side of the casing 1 shown in FIG. 5 may be disposed on the right side of the casing 1. When the operation part 6 is disposed on the right side, as will be understood from FIGS. 1 and 2, the discrimination hole 2 n is provided in the top cover 2 and the operating slot 3 i is provided in the bottom cover 3. Therefore, the operation part 6 is disposed in a reversed state.

In this case, the disk D is used with the casing 1 turned upside down, as shown in FIG. 2, and whether or not information can be written on the disk D can be arbitrarily determined by selecting the top or the bottom side of the casing 1.

An operation element 7, which is a molded article made of synthetic resin, includes a rectangular sealing part 7 a, a recess 7 b formed in the sealing part 7 a, a through hole 7 c formed in the sealing part 7 a in parallel with the through hole 7 b, and an engaging part 7 d having spring properties which extends from one end of the sealing part 7 a, as shown in FIGS. 28 and 29.

As shown in FIGS. 5 to 9, the operation element 7 is received in the receiving part 5 k and is accommodated in the accommodating section 1 a of the casing 1 in a state where the recess 7 b opposes the operating slot 2 j of the top cover 2, the blocking part 2 m of the top cover 2 is inserted into the through hole 7 c, and the through hole 7 c opposes the hole 3 q of the bottom cover 3.

When the operation element 7 is accommodated, the movement of the operation element 7 is blocked by the blocking part 2 m, the holder 5 cannot be removed from the casing 1, the upper and lower surfaces of the operation element 7 are clamped by the top and bottom covers 2 and 3, side surfaces abut against the second guide part 5 m, and the engaging part 7 d is engaged with the recess 5 n.

That is, the operation element 7 is mounted without entering into the operating slot 2 j of the top cover 2 and the discrimination holes 3 p and 3 q of the bottom cover 3.

When the disk D is accommodated in the casing 1 and the movement of the operation element 7 is blocked by the blocking part 2 m as described above, the checking for defective regions of the disk D has been completed.

As shown in FIGS. 6 and 7, when the operation element 7 is at a position near the front of the casing 1, the discrimination hole 3 p is closed by the sealing part 7 a of the operation element 7 to prevent the detection pin (not shown), provided on the disk driving apparatus, from entering the discrimination hole 3 p so that the completion of the checking for defective regions of the disk D is detected.

The user, however, may desire to replace the disk D in the casing 1 with another disk D from necessity.

In this case, the blocking part 2 m is first broken by the operation tool (not shown) from behind the hole 3 p or the blocking part 2 m so as to allow the holder 5 and the operation element 7 to be removed from the casing 1.

When the holder 5 is removed from the casing 1, the operation element 7 is pulled out by the second receiving parts 5 k and the disk D is pulled out by the elastic arms 5 b. After the replacement of the disk D with another disk D, the second disk D and the operation element 7 are accommodated again in the accommodating section 1 a of the casing 1 together with the holder 5.

The accommodated second disk D is not subjected to checking for defective regions. Therefore, when the operation tool (not shown) is passed through the operating slot 2 j to be engaged with the recess 7 b of the operation element 7, and the operation element 7 is slid along the operating slot 2 j in a direction to separate from the front of the casing 1, the operation element 7 slides using the second guide part 5 m, and the engaging part 7 d engages with another recess 5 n, whereby the operation element 7 is positioned, as shown in FIGS. 8 and 9.

In this case, the sealing part 7 a of the operation element 7 opens the discrimination hole 3 p and enables the entry of the detection pin so as to determine that defective regions of the disk D have not yet been detected.

When a defective region of the disk D is detected by the disk driving apparatus in the state shown in FIG. 8, the casing 1 is removed from the disk driving apparatus, and the operation element 7 is slid by the operation tool so as to bring about the state shown in FIG. 6.

Thereafter, it is determined that the checking for defective regions of the disk D has been completed.

The operation element 7 disposed on the left side of the casing 1 shown in FIG. 5 may be disposed on the right side of the casing 1. When the operation element 7 is disposed on the right side, as will be understood from FIGS. 1 and 2, the discrimination hole 2 p is provided in the top cover 2 and the operating slot 3 j is provided in the bottom cover 3. Therefore, the operation element 7 is disposed in a reversed state.

In this case, the disk D is used with the casing 1 turned upside down, as shown in FIG. 2. Therefore, the blocking part 3 m is broken so as to enable the movement of the operation element 7 and to determine whether or not the checking for defective regions has been completed.

The blocking parts 2 m and 3 m may be provided separately from the top and bottom covers 2 and 3.

In this case, holes 2 q and 3 q may be provided at the positions of the blocking parts 2 m and 3 m, and separate blocking parts 2 m and 3 m may be inserted into the holes 2 p and 3 q. Assembling of such a disk cartridge is completed by combining the top and bottom covers 2 and 3 to form the casing 1, by accommodating the disk D, the operation part 6, and the operation element 7 in the casing 1, and then by mounting the separate blocking parts 2 m and 3 m. This facilitates manufacture of the optical disk cartridge.

As described above, the optical disk cartridge can be accurately assembled by the incorrect-insertion-preventing sections A of the casing 1 and the incorrect-insertion-preventing sections B of the holder 5 at the time of replacement of the disk D, and the top and bottom faces of the holder 5 or the optical disk cartridge can be securely identified by the identification mark 5 p when assembling the holder 5 or when using the optical disk cartridge.

When the optical disk cartridge constructed as described above is loaded on a disk driving apparatus 8, the shutter 4 is moved to open the clamping windows 2 s and 3 s and the reading and writing windows 2 t and 3 t, as shown in FIG. 10.

When the disk D is loaded, the detection pins (not shown) enter into the discrimination holes 3 n and 3 p, respectively, to determine whether or not information can be written on the disk D and whether or not the checking for defective regions has been completed. In addition, a table 9 is rotated about a fulcrum 9 a to allow a spindle 10 a of a motor 10 attached on the table 9 to be inserted into a hole of the disk D and to allow a hub 10 b to abut against the face of the disk D, whereby the disk D is clamped.

An optical head 11 is moved in the vertical direction E (shown in FIG. 11) with the disk D rotated by the motor 10 so as to write information on the disk D or read information from the disk D.

The outer diameter of the hub 10 b generally ranges from 25 to 29 mm. In consideration of the movement of the shutter 4 without extruding from the casing 1, the width H of the clamping windows 2 s and 3 s in the horizontal direction F is ±2 mm of 27.4 mm. Moreover, since the hub 10 b moves in a circle about the fulcrum 9 a of the table 9, the diameter G of the clamping windows 2 s and 3 s in the vertical direction E is ±2 mm of 28 mm.

By enlarging the size of the clamping windows 2 s and 3 s in the vertical direction E, the hub 10 b can be prevented from colliding with the casing 1 during the circular motion thereof. In addition, by reducing the size of the clamping windows 2 s and 3 s in the horizontal direction F, the amount of movement of the shutter 4 can be secured.

The optical disk cartridge of the present invention includes the casing 1 having a pair of walls 2 a and 3 a for accommodating the disk D therein. The walls 2 a and 3 a of the casing 1 are formed with clamping windows 2 s and 3 s for clamping the disk D at the central portions thereof, and are formed with reading and writing windows 2 t and 3 t for reading information from the disk D and writing information on the disk D from the clamping windows 2 s and 3 s to the side edges of the casing 1, the shutter 4 capable of opening and closing the clamping windows 2 s and 3 s and the reading and writing windows 2 t and 3 t is slidably provided, and the horizontal size H of the clamping windows 2 s and 3 s along a sliding direction of the shutter 4 is formed shorter than the vertical size G thereof orthogonal to the sliding direction of the shutter 4. Therefore, the size of the clamping windows 2 s and 3 s can be reduced so as to prevent the clamper and the hub 10 b from colliding with the walls 2 a and 3 a due to the circular motion thereof, and the size of the optical disk cartridge can be reduced so that the shutter 4 is not extruded from the casing 1.

The clamping windows 2 s and 3 s are formed by linear parts K opposing along the sliding direction of the shutter 4, and arcuate parts J connecting the linear parts K, and the distance H between the linear parts K is shorter than the diameter G of the arcuate parts J. Therefore, the shape of the optical disk cartridge can be simplified, and the linear parts K are shaped along the reading and writing windows 2 t and 3 t and the side edges of the shutter 4. In addition, the clamping windows 2 s and 3 s can be opened and closed as the shutter 4 opens and closes the reading and writing windows 2 t and 3 t.

The diameter of the arcuate parts J of the clamping windows 2 s and 3 s is ±2 mm of 28 mm, and the distance between the linear parts K is be ±2 mm of 27.4 mm. Therefore, the amount of movement of the shutter can be secured such that it is not extruded from the casing 1, and the size of the optical disk cartridge can be reduced such that the hub 10 b can be inserted. In particular, the optical disk cartridge is suitable for use with 80 mm disks.

The projections 2 u and 3 u for narrowing the width of the reading and writing windows 2 t and 3 t are formed on the border of the clamping windows 2 s and 3 s and the reading and clamping windows 2 t and 3 t. Therefore, when the shutter 4 repeatedly opens and closes the clamping windows 2 s and 3 s and the reading and writing windows 2 t and 3 t, the engagement between the shutter 4 and the side edges of the clamping windows 2 s and 3 s and the reading and writing windows 2 t and 3 t can be reduced, and the shutter 4 can be smoothly moved. 

What is claimed is:
 1. An optical disk cartridge comprising a casing having a pair of walls for accommodating an optical disk therein; wherein said walls of the casing each comprise a clamping window for clamping said disk at the central portion thereof, and a reading and writing window for reading information from said disk and writing information on to said disk, said reading and writing window extending from a perimeter of said clamping window to a side edge of said casing; wherein a shutter capable of opening and closing each of said clamping windows and each of said reading and writing windows is slidably provided on said casing; wherein the perimeter of said clamping window comprises a pair of opposing linear portions connected between a pair of opposing arcuate portions, said linear portions each extending orthogonally to a sliding direction of the shutter and intersecting with a line that extends parallel to the sliding direction of said shutter and passes through a rotational axis of the optical disc, said arcuate portions comprising arc segments of a single circle having a radii that intersects the rotational axis of said optical disc; and wherein a lateral width of each of said clamping windows as measured between the pair of opposing linear portions and along the line intersecting the rotational axis of said optical disk and parallel to the sliding direction of said shutter is formed shorter than a longitudinal length of said clamping windows as measured between the pair of opposing arcuate portions and along the radii intersecting said rotational axis of said optical disk.
 2. The optical disk cartridge according to claim 1, wherein the width between the opposing pair of linear portions of each of said clamping windows, as measured along the line intersecting the rotational axis of said optical disk and parallel to the sliding direction of said shutter, is ±2 mm of 27.4 mm.
 3. The optical disk cartridge according to claim 1, wherein projections for narrowing the width of said reading and writing windows are formed on the border of said clamping windows and said reading and clamping windows.
 4. The optical disk cartridge according to claim 1, wherein the longitudinal length between the opposing pair of arcuate portions of each of said clamping windows, as measured along the radii intersecting the rotational axis of said optical disk and orthogonal to the sliding direction of said shutter, is ±2 mm of 28 mm. 